Care-free perennials: butterfly weed

October 9, 2015

If your yard includes an area that's hot and dry, light it up with butterfly weed, Asclepias tuberosa. This durable native plant is a little slow to get started, but once established it thrives on neglect. These guidelines will give you the know-how on growing butterfly weed.

Care-free perennials: butterfly weed

1. Butterfly weed in the landscape

The butterfly weed is a handsome, compact plant that blazes gloriously for many weeks in midsummer when it displays a crown of waxy, bright orange flowers. Easily seen from afar but also interesting up close, butterfly weed's dense flower clusters comprise many small flowers, each with a yellow centre and back-flung petals.

Despite wilting heat, the flowers stand firm on 0.6-metre-tall (two-foot-tall) rigid stems framed by leathery drought-resistant foliage. In late summer you will have to choose between coaxing the plant to produce a second flush of bloom by cutting off the old flowers or letting them ripen into ornamental seedpods.

Use masses of butterfly weed in sunny wildflower borders and on sunny slopes that are too rugged for other plants to thrive. In warm-summer climates, butterfly weed does fine in full sun, but it can also be grown in partial shade.

2. Other shades of butterfly weed

In the wild, butterfly weed flowers are always bright tangerine, though variations that shift towards yellow or red hues are not uncommon.

  • For a white-flowered version, try A. incarnata 'Ice Ballet', which stands substantially taller, at one metre (three feet).
  • Other cultivated selections of A. incarnata have pink flowers and are often called swamp milkweed.

As the name suggests, this species does best in a moist soil. Unfortunately, aphids love this species more than the orange butterfly weed, making it somewhat less care-free.

3. Growing butterfly weed

  • To get butterfly weed off to a strong start, set out container-grown plants in spring.
  • Refrain from digging plants when they are actively growing, because the risk of breaking the brittle taproot and losing the plant is high.
  • A kinder way to propagate plants is to take 10 centimetre (four inch) stem cuttings in spring, strip off leaves from the lower half of the stem and insert them half its length into a mixture of damp sand and peat moss.
  • Keep the soil around cuttings moist and shade them until they are well rooted, then plant them in the garden.
  • Give new plants occasional water if a serious drought strikes the first summer after planting, and keep weeds pulled away from the growing points, or crowns.
  • By their third summer, the plants should have thick tuberous roots and be able to fend for themselves in any type of weather. Except for butterfly larvae (caterpillars), which eat leaves, pests are few.
  • Bright yellow aphids sometimes appear in large numbers on new growth. You can simply rinse them off with water from a hose, pick off and dispose of infested leaves or apply insecticidal soap per label directions.

4. A bevy of butterflies

Monarch caterpillars and several other species feed on butterfly weed foliage. Try to relocate them to plants that are out of sight so that the caterpillars can mature into majestic orange-and-black butterflies.

If you intend to let some plants serve as butterfly nurseries, locate them behind other flowers where the tattered foliage will not show in summer. Many other butterfly species also visit the plant to sip the blossoms' sweet nectar.

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